U.S. patent number 9,427,592 [Application Number 14/012,634] was granted by the patent office on 2016-08-30 for systems and methods for low energy wake-up and pairing for use with implantable medical devices.
This patent grant is currently assigned to Pacesetter, Inc.. The grantee listed for this patent is Pacesetter, Inc.. Invention is credited to Reza Shahandeh, Thanh Tieu, Yongjian Wu, Jun Yang, Min Yang, Chao-Wen Young.
United States Patent |
9,427,592 |
Wu , et al. |
August 30, 2016 |
Systems and methods for low energy wake-up and pairing for use with
implantable medical devices
Abstract
Techniques are provided for use with implantable medical devices
or trial medical devices for wirelessly connecting the devices to
external instruments such as tablet computers or smartphones. In an
example where the medical device is an implantable neurostimulator,
the neurostimulator passively detects wireless wake-up signals
generated by the external instrument, i.e. the neurostimulator
"sniffs" for advertisement signals generated by the external
instrument. In response to passive detection of a wake-up signal,
the implantable neurostimulator determines if a response is
warranted and, if so, the neurostimulator activates its wireless
transmission components to transmit an acknowledgement signal to
the external instrument so as to complete a wake-up and handshake
protocol. In this manner, power consumption within the implantable
device (or within a similarly equipped trial medical device) can be
reduced compared to devices that would otherwise periodically
transmit advertisement signals even when no external mobile
instrument is present.
Inventors: |
Wu; Yongjian (Saratoga, CA),
Young; Chao-Wen (Cupertino, CA), Yang; Jun (Valencia,
CA), Shahandeh; Reza (Thousand Oaks, CA), Tieu; Thanh
(Simi Valley, CA), Yang; Min (Los Altos, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Pacesetter, Inc. |
Los Gatos |
CA |
US |
|
|
Assignee: |
Pacesetter, Inc. (Sunnyvale,
CA)
|
Family
ID: |
52583903 |
Appl.
No.: |
14/012,634 |
Filed: |
August 28, 2013 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20150065047 A1 |
Mar 5, 2015 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
4/80 (20180201); A61N 1/36071 (20130101); A61N
1/37235 (20130101); A61N 1/37276 (20130101) |
Current International
Class: |
A61N
1/372 (20060101); H04W 4/00 (20090101); A61N
1/36 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1 895 438 |
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Jul 2007 |
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EP |
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1 583 585 |
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Jun 2008 |
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EP |
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2 426 865 |
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Mar 2012 |
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EP |
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2 540 343 |
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Jun 2012 |
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EP |
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Primary Examiner: Hsieh; Ping
Assistant Examiner: Yang; James
Attorney, Agent or Firm: Raymer; Theresa A.
Claims
What is claimed is:
1. A method for use by an implantable medical device for implant
within a patient, the method comprising: passively detecting
wireless wake-up signals generated by an external instrument
equipped to communicate with the implantable medical device,
wherein the external instrument is one of a plurality of external
instruments capable of communicating with the implantable medical
device, and wherein at least some of the plurality of external
instruments are not authorized to communicate with the implantable
medical device; and in response to passive detection of a wake-up
signal from the external instrument, determining if a response to
the wake-up signal is warranted and, if so, activating wireless
signal transmission components of the implantable medical device
and transmitting an acknowledgement signal to the external
instrument, wherein determining if a response to the wake-up signal
is warranted includes determining if the external instrument
generating the wake-up signal is authorized to wake up the
implantable medical device based on a coded signal received from
the external instrument that indicates the external instrument is
authorized to wake up the implantable medical device and that
differs from coded signals from at least some other external
instruments capable of communicating with the implantable medical
device but not authorized to wake up the implantable medical
device.
2. The method of claim 1 wherein the wake-up signals are short
range wireless wake-up signals received by a component of the
implantable medical device.
3. The method of claim 2 wherein the short range wireless wake-up
signals are advertisement signals generated in accordance with a
low energy short range wireless communication standard.
4. The method of claim 2 wherein passively detecting wake-up
signals includes short range wireless communication sniffing.
5. The method of claim 1 wherein passively detecting wake-up
signals is performed using wireless signal reception components of
the implantable medical device and wherein, in the absence of
detection of a wake-up signal warranting a response, the wireless
signal reception components of the implantable medical device enter
a sleep mode pending a next passive detection cycle.
6. The method of claim 1 wherein passively detecting short range
wireless communication wake-up signals generated by an external
instrument includes initiating a passive scan search period and,
during at least a portion of the scan search period, sniffing for
any wireless wake-up signals generated by instruments that are
external to the patient; and wherein, if at least one wireless
wake-up signal is detected during the scan search period, then
waiting until completion of the scan search period before
activating the short range wireless signal transmission components
and transmitting the acknowledgement signal to the external
instrument that generated the detected wireless wake-up signal.
7. The method of claim 1 wherein determining if a response to the
wake-up signal is warranted includes determining if a particular
software component of the particular external instrument generating
the wake-up signal is authorized to wake up the implantable medical
device based on a coded signal received from the external
instrument that indicates the particular software component is
authorized to wake up the implantable medical device and that
differs from coded signals associated with at least some other
software components capable of generating coded signals for
transmission to the implantable medical device but not authorized
to wake up the implantable medical device.
8. The method of claim 1 wherein the wake-up signal includes
identifying information for identifying the external instrument or
a component thereof and additional information beyond the
identifying information and wherein, if a response to the wake-up
signal is warranted, the implantable medical device also responds
to the additional information.
9. A method for use by an implantable medical device for implant
within a patient and an external instrument equipped to communicate
with the implantable medical device, the method comprising:
generating wireless wake-up signals using the external instrument;
passively detecting the wireless wake-up signals generated by the
external instrument using the implantable medical device where the
external instrument is one of a plurality of external instruments
capable of communicating with the implantable medical device, and
wherein at least some of the plurality of external instruments are
not authorized to communicate with the implantable medical device;
in response to passive detection of a wake-up signal by the
implantable medical device, determining if a response to the
wake-up signal is warranted and, if so, activating wireless signal
transmission components of the implantable medical device and
transmitting an acknowledgement signal to the external instrument,
wherein determining if a response to the wake-up signal is
warranted includes determining if the external instrument is
authorized to wake up the implantable medical device based on a
coded signal received from the external instrument that indicates
the external instrument is authorized to wake up the implantable
medical device and that differs from coded signals from at least
some other external instruments capable of communicating with the
implantable medical device but not authorized to wake up the
implantable medical device; and in response to detection by the
external instrument of the acknowledgement signal, engaging in
further wireless communications between the external instrument and
the implantable medical device.
10. The method of claim 9 wherein the wake-up signals are short
range wireless wake-up signals received by a component of the
implantable medical device.
11. The method of claim 10 wherein the short range wireless wake-up
signals generated by the external instrument are advertisement
signals generated in accordance with a low energy short range
wireless communication standard.
12. The method of claim 10 wherein the passive detection of wake-up
signals by the implantable medical device includes short range
wireless sniffing.
13. The method of claim 9 wherein passive detection of wake-up
signals by the implantable medical device is performed using
wireless signal reception components of the implantable medical
device and wherein, in the absence of detection of a wake-up signal
warranting a response, the wireless signal reception components of
the implantable medical device enter a sleep mode pending a next
passive detection cycle.
14. A system for use by an implantable medical device for implant
within a patient, the system comprising: passive signal reception
components operative to passively detect wireless wake-up signals
generated by an external instrument equipped to communicate with
the implantable medical device where the external instrument is one
of a plurality of external instruments capable of communicating
with the implantable medical device, wherein at least some of the
plurality of external instruments are not authorized to communicate
with the implantable medical device; wake-up signal processing
components operative in response to passive detection of a wake-up
signal from the external instrument to determine if a response is
warranted including determining if the external instrument
generating the wake-up signal is authorized to wake up the
implantable medical device based on a coded signal received from
the external instrument that indicates the external instrument is
authorized to wake up the implantable medical device and that
differs from coded signals from at least some other external
instruments capable of communicating with the implantable medical
device but not authorized to wake up the implantable medical
device; and active signal transmission components operative if a
response is warranted to transmit a wireless acknowledgement signal
to the external instrument.
15. The system of claim 14 wherein the passive signal reception
components are further operative to initiate a passive scan search
period and, during at least a portion of the scan search period,
sniff for any wireless wake-up signals generated by instruments
that are external to the patient; and wherein the active signal
transmission components are further operative, in response to
detection of at least one wireless wake-up signal during the scan
search period, to wait until completion of the scan search period
before transmitting the acknowledgement signal to the external
instrument that generated the detected wireless wake-up signal.
16. The system of claim 14 wherein the wake-up signal processing
components are further operative to determine if a particular
software component of the particular external instrument generating
the wake-up signal is authorized to wake up the implantable medical
device based on a coded signal received from the external
instrument that indicates the particular software component is
authorized to wake up the implantable medical device and that
differs from coded signals associated with at least some other
software components capable of generating signals for transmission
to the implantable medical device but not authorized to wake up the
implantable medical device.
17. The system of claim 14 wherein the wake-up signal includes
identifying information for identifying the external instrument or
a component thereof and additional information beyond the
identifying information and wherein the system is further operative
to respond to the additional information.
18. The system of claim 14, wherein the wake-up signals are short
range wireless wake-up signals received by a component of the
implantable medical device.
19. A method for use by a trial medical device having at least one
lead for implant within a patient, the method comprising: passively
detecting wireless wake-up signals generated by an external
instrument equipped to communicate with the trial medical device
where the external instrument is one of a plurality of external
instruments capable of communicating with the trial medical device,
wherein at least some of the plurality of external instruments are
not authorized to communicate with the trial medical device; and in
response to passive detection of a wake-up signal from the external
instrument, determining if a response is warranted and, if so,
activating wireless signal transmission components of the trial
medical device and transmitting an acknowledgement signal to the
external instrument, wherein determining if a response to the
wake-up signal is warranted includes determining if the external
instrument generating the wake-up signal is authorized to wake up
the trial medical device based on a coded signal received from the
external instrument that indicates the external instrument is
authorized to wake up the trial medical device and that differs
from coded signals from at least some other external instruments
capable of communicating with the trial medical device but not
authorized to wake up the trial medical device.
20. The method of claim 19 wherein passively detecting short range
wireless communication wake-up signals generated by an external
instrument includes initiating a passive scan search period and,
during at least a portion of the scan search period, sniffing for
any wireless wake-up signals generated by instruments that are
external to the patient; and wherein, if at least one wireless
wake-up signal is detected during the scan search period, then
waiting until completion of the scan search period before
activating the short range wireless signal transmission components
and transmitting the acknowledgement signal to the external
instrument that generated the detected wireless wake-up signal.
21. The method of claim 19 wherein determining if a response to the
wake-up signal is warranted includes determining if a particular
software component of the particular external instrument generating
the wake-up signal is authorized to wake up the trial medical
device based on a coded signal received from the external
instrument that indicates the particular software component is
authorized to wake up the trial medical device and that differs
from coded signals associated with at least some other software
components capable of generating signals for transmission to the
implantable medical device but not authorized to wake up the trial
medical device.
22. The method of claim 19 wherein the wake-up signal includes
identifying information for identifying the external instrument or
a component thereof and additional information beyond the
identifying information and wherein, if a response to the wake-up
signal is warranted, the trial medical device also responds to the
additional information.
23. A method for use by a trial medical device having at least one
lead for implant within a patient and an external instrument
equipped to communicate with the trial medical device, the method
comprising: generating wireless wake-up signals using the external
instrument; passively detecting the wireless wake-up signals
generated by the external instrument using the trial medical device
where the external instrument is one of a plurality of external
instruments capable of communicating with the trial medical device,
and wherein at least some of the plurality of external instruments
are not authorized to communicate with the trial medical device; in
response to passive detection of a wake-up signal by the trial
medical device, determining if a response is warranted and, if so,
activating wireless signal transmission components of the trial
medical device and transmitting an acknowledgement signal to the
external instrument, wherein determining if a response to the
wake-up signal is warranted includes determining if the external
instrument generating the wake-up signal is authorized to wake up
the trial medical device based on a coded signal received from the
external instrument that indicates the external instrument is
authorized to wake up the trial medical device and that differs
from coded signals from at least some other external instruments
capable of communicating with the trial medical device but not
authorized to wake up the trial medical device; and in response to
detection by the external instrument of the acknowledgement signal,
engaging in further wireless communications between the external
instrument and the trial medical device.
Description
FIELD OF THE INVENTION
The invention generally relates to implantable medical devices such
as full or trial neurostimulation devices and, in particular, to
techniques for controlling communication between such devices and
external mobile computing instruments such as smartphones and
tablet computers.
BACKGROUND OF THE INVENTION
Implantable neurostimulation devices can be employed to manage pain
arising from a variety of conditions such as failed back surgery
syndrome, post-laminectomy syndrome or other neuropathies. To this
end, a spinal cord stimulation (SCS) device or other
neurostimulator may be implanted within the body to deliver
electrical pulses to nerves or other tissues. The neurostimulator
typically includes a small pulse generator device similar to a
pacemaker but equipped to send electrical pulses to leads mounted
along the nerves near the spinal cord or elsewhere. For SCS, the
generator is often implanted in the abdomen or buttock area. The
stimulation leads may include thin wires or paddles for delivering
electrical pulses to patient nerve tissues. An external controller,
similar to a remote control device, may be provided to allow the
patient to control or adjust the neurostimulation. Currently, prior
to permanent (i.e. chronic) implant of a neurostimulator, the
patient undergoes a trial period during which he or she is
implanted with a lead that is externalized and connected to a trial
neurostimulation control device, which the patient carries with him
or her. Herein, the external neurostimulation control device used
during the trial period is referred to as a trial neurostimulator
or trial neurostimulation device.
State-of-the-art implantable neurostimulators and trial
neurostimulators are being designed to communicate with tablet
computers, smartphones and other mobile instruments to allow the
patient or clinician to control the operation of the device,
retrieve diagnostic data, etc. For example, dedicated application
software (i.e. an "app") running on a tablet computer could be used
to adjust the frequency or amplitude of neurostimulation applied to
the spine by an SCS device to allow the patient to improve pain
reduction. In particular, Bluetooth Low Energy (BLE) telemetry
protocols can be used to control communication between a mobile
instrument and an implantable neurostimulator or trial
neurostimulator. Issues, however, arise in implementing such a
communication scheme. App designers typically have minimal control
over the behavior of the mobile device platform, which may comprise
a commercially off-the-shelf mobile instrument employing build-in
drivers and operating systems. The designers of apps for
communicating with neurostimulation devices may have only a limited
level of configuration control on the BLE protocol stack.
Furthermore, conservation of the power supply of an implantable
medical device is a key design issue. It is important to avoid
undue depletion of battery resources. This is particularly true
insofar as "wake-up and pairing" is concerned wherein the
implantable neurostimulator and the mobile instrument detect one
another's presence and establish secure communications. Similar
concerns apply to external trial neurostimulators, which may be
provided with only minimal power resources since the trial period
is typically a month or less. Accordingly, there is the need to
implement a wake-up and pairing scheme that provides a robust link
with minimal impact on the longevity of neurostimulator devices or
other implantable or trial medical devices.
However, the standard wake-up and pairing scheme for connecting a
Bluetooth accessory device (i.e. a slave device) to a mobile
instrument (such as a tablet computer) is for the accessory device
to periodically "advertise" itself so that a mobile instrument in
the vicinity might be alerted to its presence. The mobile
instrument then tags to one of the advertising pulses and requests
a connection, i.e. an initial "handshake" is performed. Pairing or
normal link establishment then follows the initial handshake.
However, most of the advertisement signals generated by the
accessory device are unheeded because no mobile instrument is
nearby to establish a connection. For implantable neurostimulators,
the standard wake-up and pairing scheme could significantly deplete
the battery resources of the implanted device. Similar battery
depletion problems can arise during a trial neurostimulation period
when wirelessly connecting an external trial neurostimulator to a
mobile instrument. Still further, problems can arise involving
malicious "spoofing" or "hacking" if the neurostimulator is
programmed to transmit frequent advertisement signals that a rogue
external instrument might intercept. Indeed, even if the
neurostimulator properly rejects communication requests with a
rogue device, considerable battery energy could be wasted while the
neurostimulator filters out the invalid requests. Similar problems
could also occur with other implantable medical devices such as
pacemakers if equipped to communicate with external instruments
using Bluetooth or other wireless communication protocols.
Accordingly, it would be highly desirable to provide improved
techniques for performing wake-up and pairing (or similar
protocols) between implantable/external medical devices and mobile
instruments such as tablet computers. It is to these ends that
aspects of the invention are generally directed.
SUMMARY OF THE INVENTION
In an exemplary embodiment, a method is provided for use with an
implantable medical device or trial medical device to wirelessly
connect the device to an external instrument such as a tablet
computer or smartphone. In one example, where the medical device is
an implantable device such as an SCS device, the implantable device
passively detects wireless wake-up signals generated by the
external instrument, e.g. the implantable device "sniffs" for
advertisement signals generated by the external instrument. In
response to passive detection of a wake-up signal from the external
instrument, the implantable device determines if a response is
warranted (i.e. the detected signal is a valid wake-up signal) and,
if so, the implantable device activates its wireless transmission
components to transmit an acknowledgement signal to the external
instrument so as to complete a wake-up and handshake protocol.
Hence, rather than have the implantable device generate and
transmit advertisement signals for the external instrument to
detect, the external instrument is instead programmed to generate
advertisement signals that the implantable device passively detects
and selectively responds to. The implantable device does not
proceed to link establishment unless a valid wake-up signal is
received from an authorized external instrument. In this manner,
power consumption within the implantable medical device (or within
a similarly equipped trial medical device) can be reduced compared
to devices that would otherwise periodically generate and transmit
advertisement signals even when no authorized external instrument
is present. Still further, the risk that the medical device might
be "spoofed" or "hacked" by a rogue device is reduced since the
medical device only responds to valid advertisement signals from a
properly authorized external instrument. Moreover, the medical
device need not waste energy filtering out frequent communication
requests from rogue devices, since the medical device will not be
advertising itself to those devices.
In an illustrative embodiment, the implantable device is a
neurostimulator and the external instrument is a mobile device
(e.g. tablet computer, smartphone, etc.) The neurostimulator and
the external mobile instrument are both Bluetooth-enabled devices
equipped to implement BLE communication protocols or standards.
Telemetry components of the implantable neurostimulator remain in a
sleep mode until a passive detection cycle is initiated which may
occur, for example, once every five to ten seconds. During the
passive detection cycle, the neurostimulator "sniffs" for BLE
advertisement signals generated by any mobile instruments that
might be in the vicinity. If no such signal is detected, the
telemetry components return to the sleep mode pending the next
sensing cycle. Assuming, however, that a BLE advertisement signal
is detected, the neurostimulator examines the advertisement signal
to determine if it represents a valid wake-up signal that warrants
a response, e.g. the signal includes appropriate identification
codes indicating it was sent by a device authorized to communicate
with the particular neurostimulator. If the advertisement signal is
deemed to be a valid wake-up signal, the neurostimulator activates
its signal transmission components to transmit a suitable
responsive handshake signal to the mobile instrument. Thereafter,
the mobile instrument can transmit appropriate signals to the
neurostimulator to, for example, retrieve diagnostic data from
device memory for display on the mobile instrument or to adjust the
programming of the neurostimulator. In examples where the
neurostimulator is an SCS device, the mobile instrument might be
used to change the frequency, duration or amplitude of SCS. Further
improvement on the discovery latency can be achieve by making the
external instrument perform active advertising upon app activation
by the user.
Still further, in the illustrative embodiment, the advertisement
signals generated by the mobile instrument are generated only in
response to user input provided via an application specific program
("app") whereupon the mobile instrument transmits a burst of
"advert" signals with one signal every 20 milliseconds (ms) or so.
Such bursts of advert signals can be repeated during an interval of
five to ten seconds to allow the neurostimulator to detect the
signals during one of its sensing cycles to permit wake-up and
handshake. (By setting the sensing cycle of the neurostimulator to
five to ten seconds, the latency between a communication request
from the mobile instrument and its acknowledgement is generally
acceptable, i.e. it is not too long.) Thereafter, further wireless
communications proceed under the control of the user via the
software app until the user terminates the communication session or
either the neurostimulator or the mobile instrument otherwise
terminates the session. By having the mobile instrument only
generate advert signals in response to user input, the procedure
also helps avoid undue depletion of power resources of the mobile
instrument.
Although described herein primarily with respect to communications
between an implantable medical device and an external mobile
computing device such as a tablet computer, aspects of the
invention are also applicable to communications between external
instruments and trial medical devices that are external to the
patient but include one or more leads for implant within the
patient, or to trial medical devices for removable implant within
the patient.
System and method examples are described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and further features, advantages and benefits of the
invention will be apparent upon consideration of the descriptions
herein taken in conjunction with the accompanying drawings, in
which:
FIG. 1 illustrates an exemplary neurostimulation system having an
implantable SCS device equipped for power-efficient
wake-up/handshake with a mobile instrument such as a tablet
computer;
FIG. 2 provides an overview of a power-efficient wake-up/handshake
method for use by the implantable medical device of FIG. 1 or
similarly-equipped trial medical devices;
FIG. 3 provides an exemplary power-efficient wake-up/handshake
procedure in accordance with the general method of FIG. 2 for an
example where an implantable SCS device (or external trial SCS
device) communicates with a mobile instrument by exploiting BLE
protocols;
FIG. 4 illustrates exemplary BLE signal sequences for both a power
inefficient wake-up/handshake protocol and a preferred power
efficient protocol use with the methods of FIGS. 3 and 4;
FIG. 5 is a block diagram illustrating pertinent components of the
implantable neurostimulator device of FIG. 1; and
FIG. 6 illustrates an alternative neurostimulation system to that
of FIG. 1 wherein the SCS device is an external trial device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description includes the best mode presently
contemplated for practicing the invention. This description is not
to be taken in a limiting sense but is made merely to describe
general principles of the invention. The scope of the invention
should be ascertained with reference to the issued claims. In the
description of the invention that follows, like numerals or
reference designators are used to refer to like parts or elements
throughout.
Overview of Neurostimulation System and External Mobile
instrument
FIG. 1 illustrates an exemplary implantable medical system 8 having
an implantable SCS device 10 (or "pulse generator") equipped for
power-efficient wake-up/handshake with an external mobile
instrument 12 such as a tablet computer or smartphone, which may be
referred to as a "Neuro External" device. SCS device 10 includes
one or more paddles or electrodes 14 implanted along the spine for
delivering neurostimulation using one or more stimulation sets
(Stim Sets) initially specified by a clinician. The Stim Sets
specify SCS parameters for controlling delivery of SCS to nerve
tissues of the patient to address the needs of the patient, such as
to reduce pain or to achieve desired cardioprotective effects. The
clinician or the patient can then change the Stim Sets using the
mobile instrument (via a Bluetooth wireless radio communication
link 15) to activate, deactivate or adjust the neurostimulation,
such as by changing the amplitude, frequency or duration of
stimulation pulses generated by the SCS device. The mobile
instrument can also be used to retrieve diagnostic data from the
SCS device including data pertaining to remaining battery power
(i.e. battery life) or other operational parameters of the device.
As will be explained in more detail below, communication between
the SOS device and the mobile instrument preferably exploits a
power-efficient wake-up/handshake protocol that reduces overall
power consumption by the SCS device while also reducing the risk of
"spoofing" or "hacking" by rogue external instruments.
Mobile instrument 12 may also communicate with a remote or
centralized data processing/data storage system 16 via the Internet
or other suitable communication channels/networks to relay
information to the primary care physician of the patient or to
other appropriate clinicians. The centralized system may include
such systems as the HouseCall.TM. remote monitoring system or the
Merlin@home/Merlin.Net systems of St. Jude Medical. Note that,
although the example of FIG. 1 shows an SCS device 10 for
stimulating the spinal cord, additional or alternative stimulation
devices might be employed, such as devices for stimulating other
tissues or organs within the patient. Some patients might
additionally or alternatively have an implantable cardiac rhythm
management device (CRMD) such as a pacemaker, implantable
cardioverter-defibrillator (ICD) or a cardiac resynchronization
device (CRT.) At least some of the techniques described herein are
generally applicable to any of a variety of implantable medical
devices and to any of a variety of external trial devices (such as
the trial SCS device shown in FIG. 6, and discussed below.) Note
also that FIG. 1 is a stylized illustration that does not
necessarily set forth the precise locations of the implantable
components nor their relative sizes or shapes.
Exemplary Power-Efficient Wake-Up/Handshake Systems and Methods
FIG. 2 broadly summarizes a power-efficient wake-up/handshake
procedure for use by an implantable medical device or external
trial medical device. For the purposes of these descriptions, it
will be assumed that the device is an implantable medical device
such as a chronically-implanted SCS device but it should be
understood that corresponding techniques can be used with an
external trial medical devices as well. Beginning at step 100, the
implantable device passively senses or detects (e.g. sniffs) radio
frequency (RF) wireless wake-up signals (e.g. advertisement
signals) generated by an external mobile instrument such as a
tablet computer or smartphone equipped to communicate with the
medical device using Bluetooth communication protocols or other
suitable wireless communication protocols. At step 102, in response
to passive detection of one or more wake-up signals from the mobile
instrument, the implantable device examines the wake-up signals to
determine if a response is warranted. In this regard, the
implantable device determines if the wake-up signals are valid or
legitimate signals sent from an approved mobile instrument running
an approved "app" authorized to communicate with the particular
implantable device. This may be determined, for example, based on
suitable codes within the BLE configuration profile associated with
the wake-up signals.
At step 104, if a response to the wake-up signal is warranted, the
implantable device activates its wireless signal transmission
components to transmit a "handshake" acknowledgement signal to the
mobile instrument so as to establish or commence further
communications. In this manner, the wireless signal transmission
components of the implantable device can remain inactive (e.g. in a
sleep mode) until a valid wake-up signal is received. This helps
reduce power consumption within the implantable device. At step
106, once wireless communication is fully established with the
mobile instrument, the implantable device: transmits
diagnostics/operational data to the mobile instrument; receives and
responds to programming commands received from the mobile
instrument; and/or performs other suitable actions in response to
wireless communications with the mobile instrument.
Hence, with this technique, rather than have the implantable device
generate and transmit advertisement signals for the mobile
instrument to detect, the mobile instrument is instead required to
generate advertisement signals that the implantable device
selectively responds to. In this manner, power consumption within
the implantable device can be reduced compared to implantable
devices that would otherwise periodically generate and transmit
advertisement signals even when no mobile instrument is present.
Still further, the risk that the implantable device might be
"spoofed" or "hacked" by a rogue mobile instrument is reduced.
Moreover, the implantable device need not waste energy filtering
out frequent communication requests from rogue devices, since the
implantable device will not be advertising itself to those
devices.
FIG. 3 provides further details of an illustrative implementation
wherein the implantable medical device (or external trial medical
device) as well as the mobile instrument are BLE-enabled devices.
In this particular example, the implantable device is an SCS
device. At step 200, the telemetry components of the SCS device are
in a sleep state to conserve energy. At step 202, the SCS device
periodically wakes up its passive telemetry components to "sniff
for" or "listen for" Bluetooth advertisement signals, which may be
performed, e.g., once every 5-10 seconds (or at other suitable
times to meet any latency requirements.) The "passive" telemetry
components of the device are those components of the SCS device
needed to sense or receive wireless signals. These components may
differ from any "active" telemetry components needed to actually
transmit wireless signals. Active telemetry components consume
considerably more energy within the SCS device than passive
components and hence are only activated if needed.
Meanwhile, at step 206, in response to user input (i.e. input from
the patient or clinician), the external mobile instrument transmits
rapid or dense advertisement signals (e.g. one every .about.20 ms,
which is within the BLE specified range of .about.7.5 ms to 10
seconds) during a period of five to ten seconds and awaits a reply
from the SCS device. For example, the patient may be provided with
an app for running on a tablet computer (e.g. an iPad.TM., iPod
Touch.TM., iPad Mini.TM. or Android.TM. based tablet), a smartphone
(e.g., an iPhone.TM. or Android.TM.-based cell phone) or other
suitable external mobile or portable instruments, wherein the app
is programmed and authorized to communicate with the particular SCS
device implanted within the patient. If the patient wants to adjust
the operation of the SCS device, such as to change the Stim Set,
the patient activates the app and instructs the app to initiate
communications with the SCS device. In response, the app controls
the communication chip of the mobile instrument to transmit the
appropriate advertisement signals to allow the SCS device to detect
the presence of the mobile instrument. By repeating the
advertisement signals at a relatively high frequency (e.g. one
every .about.20 ms) within a period of five to ten seconds, the
mobile instrument can be reasonably assured that the SCS device
will sense the signals during one of its sensing cycles (which, as
noted, occur every five to ten seconds.) Since these signals are
only sent following user instructions, the power supply of the
mobile instrument is not unduly affected.
Once an advertisement signal is detected, step 208, the SCS device
wakes up or activates its internal advertisement filtering
components at step 210 to verify that the advert signal is intended
for the particular SCS device and warrants a response (i.e. it is a
valid communication request.) The advert filtering components of
the SCS device may include various software or hardware components
for analyzing or examining the advert signals to determine if a
response is warranted. This may include program subroutines running
on the microcontroller of the SCS device that examine codes within
the advert signal to confirm that the particular app of the
particular mobile instrument is authorized to communicate with the
particular SCS device. In this manner, the SCS device can properly
ignore advertisement signals broadcast by other devices or other
apps, particularly any such signals that might be generated by
rogue devices seeking to spoof or hack the implantable device.
Assuming a response is warranted at step 212, the SCS device wakes
up its active telemetry components at step 214 to transmit a
handshake/acknowledgement signal back to the mobile instrument to
initiate and establish further communications. The
handshake/acknowledgement signals is received at step 216 by the
mobile instrument, which then engages in further communications
with the SCS device to query for stored diagnostic data,
selectively change Stim Sets, etc., as already discussed.
FIG. 4 contrasts a relatively power-inefficient wake-up/handshake
protocol 300 with the more power efficient protocol 302 of FIGS. 2
and 3. In the relatively inefficient protocol, advert signals 304
are generated at the beginning of each advertising period 306 by
the implantable device 308 (or external trial device), regardless
of whether or not there is a nearby mobile instrument 310. If there
is no mobile instrument, or if the mobile instrument is not
authorized to communicate with the implanted device, then the
generation and transmission of the advert signals simply wastes
device power. Assuming, though, that an authorized mobile
instrument sniffs the advert signals, a SCAN_REQ 312 is generated
by the mobile instrument and an acknowledgement signal 313 is sent
from the mobile instrument, which in turn triggers a SCAN_RSP 314
within the mobile instrument and a reply signal 315. Eventually,
additional advert signals 316 may be generated and transmitted,
which again may represent wasted energy if no authorized devices
are present. (Note that protocol 300 is not necessarily prior art
to the present invention but represents a possible alternative
protocol for use with implantable medical devices that would be
less power efficient than the improved protocol of the
invention.)
In contrast to protocol 300, when using the more power efficient
protocol 302 of FIGS. 2 and 3, the implantable device 308
periodically initiates a scan search period 318, which begins with
a SCAN_REQ 320. As noted, the scan search period may be five to ten
seconds long, depending upon device programming and latency
requirements. During at least a portion of this interval, the
implantable device sniffs for any advert signals generated by
nearby devices. In the example of FIG. 4, a mobile instrument 310
happens to be in the vicinity generating advert signals 322, which
are detected by the implantable device. At the completion of the
scan search period (at which time another SCAN_REQ 324 occurs), the
implantable device issues a responsive acknowledgment signal 325 to
the mobile instrument, which responds via a SCAN_RSP 326 and reply
signal 327. Hence, in the more efficient wake-up/handshake protocol
302, the mobile instrument does not waste energy generating and
transmitting advert signals, but instead responds to those
generated by the mobile instrument, thus providing power savings
within the implantable device. As already noted, this scheme also
reduces the risk of spoofing or hacking since the implantable
device is not advertising itself to any and all nearby devices,
including any rogue devices. Note also that in these protocols the
external instrument can be programmed to carry more information in
the adv packets so that the generator can skip scan_xx packets and
proceed directly to connect to further save power in the
handshaking process.
FIG. 5 provides a block diagram illustrating pertinent components
of the implantable device of FIG. 1 for use in implementing the
wake-up/handshake protocol of FIGS. 2-4. Briefly, implantable
device 10 includes passive wireless signal reception (i.e.
sniffing) components 402, which sense or detect RF-based wireless
advert signals using an antenna 404 (which may include the case or
housing of the device.) If advert signals are detected, an advert
filtering/authentication system 406 (or other suitable wake-up
signal processing components) determines whether the advert signal
warrants a response by, for example, determining whether the advert
was issued by an authorized app running on an authorized mobile
instrument. Active wireless transmission components 408 of the
implantable device generate responsive handshake signals for
transmission using the antenna. A controller 410 (such as a
microcontroller, application specific integrated circuit (ASIC),
etc.) controls the overall operation of the device. Power is
supplied by one or more batteries 412. Data is stored within device
memory 414. As can be appreciated, numerous other components may be
included within the device to allow it to perform its intended
functions, such as generating SCS pulses for neurostimulation,
sensing nerve signals or electrocardiac signals within the patient,
etc.
For further information regarding neurostimulation devices, see,
e.g., U.S. patent application Ser. No. 13/442,749 of Xi et al.
filed Apr. 9, 2012, entitled "Systems and Methods for Controlling
Spinal Cord Stimulation to Improve Stimulation Efficacy for Use By
Implantable Medical Devices". As noted, the procedures described
herein can also be applied to trial devices. Trial neurostimulation
devices are discussed, for example, in U.S. patent application Ser.
No. 13/940,727, filed Jul. 12, 2013 of Nabutovsky et al., entitled
"Fully Implantable Trial Neurostimulation System Configured for
Minimally-Intrusive Implant/Explant", which describes both external
trial devices as well as implantable trial devices. RF scanning
techniques for use within implantable medical devices are discussed
in U.S. Patent Application 2013/0165819 of Tieu, entitled "System
and Method for Controlling Radio Frequency Scanning Attributes of
an Implantable Medical Device."
For the sake of completeness, a trial medical device is shown in
FIG. 6. Briefly, exemplary trial medical system 8' has an external
trial SCS device 10' equipped for power-efficient wake-up/handshake
with a mobile instrument 12 such as a tablet computer or
smartphone. Trial SCS device 10' includes one or more paddles or
electrodes 14' implanted within the patient for delivering trial
neurostimulation. In this example, an implantable paddle 14' is
connected to the external trial device via a lead 13. In the
drawing, phantom lines are used to illustrate the implanted paddle
and the portion of lead 13 extending within the body of the patient
so as to clearly distinguish between components within the body and
those that are external to the patient. The clinician or the
patient can use mobile instrument 12 to activate, deactivate or
adjust trial neurostimulation via a Bluetooth wireless radio
communication link 15'. The mobile instrument can also be used to
retrieve diagnostic data from the trial device. Communication
between the trial device and the mobile instrument preferably
exploits the power-efficient wake-up/handshake protocol described
in detail above. The mobile instrument may also communicate with a
centralized/remote processing system 16 to relay data to the
physician/clinician or for other purposes.
In general, while the invention has been described with reference
to particular embodiments, modifications can be made thereto
without departing from the scope of the invention. Note also that
the term "including" as used herein is intended to be inclusive,
i.e. "including but not limited to."
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